You have got away from an abuser once, and you can do it again. Don’t allow yourself to be abused again.
I shouldn’t think, for a moment, she’ll stop you seeing the GCs - she’s a user, and she wants your help.
You can’t keep trying to change the past of her childhood by throwing money at her and enabling her appalling behaviour. She’s an adult and needs to grow up and stop with all the tantrums.
Many of us grew up in (financially) poor homes - we made our own lives as adults.
It sounds as though your ex is now more supportive, and your other daughters know how toxic she is - can you not get support from them?
You’re a Nan, not a parent of these children -,she needs to look after them. Stop enabling her -go out, let her get on with it.
As for the housing, it’s unclear whose name this is in. If it’s in your name, tell her she needs to find elsewhere to live. If it’s in her name, then you find somewhere else to live. Local councils often prioritise older people and abuse victims.
If it’s joint, then see a solicitor.
If you’re an intelligent woman now, retiring won’t make you less intelligent, but retire for your own reasons, not just because you’re exhausted with the situation.
No, I know 60 isn’t elderly, but you still need to have a happy life. This sounds all misery and stress. Abuse of older parents, by adult children, is known as elder abuse.
You are being abused, and you need to call a halt to it. It won’t be easy, but work out a plan and just do it. One step at a time.
If you need professional support, then this link might be helpful:
www.ageuk.org.uk/information-advice/health-wellbeing/relationships-family/protection-from-abuse/